Strong stretching theory for diblock copolymers in thin films

We investigate the microphases of diblock copolymers confined to thin films in the strong segregation limit. We evaluate the free energies of the possible phases and present phase diagrams for block copolymers with a cylindrical bulk phase in dependence of the film thickness and the walls' preference for one of the monomers. We find four stable types of phases, which were also found in studies based on self-consistent field theory and dynamic density functional theory. We argue that perforated lamellas are not a stable phase.